This invention relates to a system for correcting an output of an analog sensor which outputs an analog signal corresponding to a quantity of state a physical quantity such as a smoke density or a temperature.
As an output correction system for an analog sensor, there have been known a zero adjusting system and a span adjusting system. For example, in the case where a current of 4 to 20 mA is output for a change in a temperature or a smoke density, amplification characteristics of an output amplifier provided in the analog sensor are adjusted to adjust a zero point and a span (linear adjustment) of output characteristics.
However, in such a conventional output correction system, it is necessary for each analog sensor to adjust its output characteristics and thus it takes much time to set completely all of the sensors. And also this makes the adjustment operation complicated and prevents accurate analog outputs from being obtained.